Effects of different disinfectants on Listeria monocytogenes biofilm on various surfaces

Listeria monocytogenes is one of the most important foodborne pathogens that can form biofilms in food processing plants. Its ability to form biofilms leads to increased resistance to disinfectants and inefficient disinfection, posing a serious threat to the food industry and ultimately to the consumer. In recent years, significant progress has been made in laboratory studies in terms of the function of stress resistance mechanisms in biofilm formation and their resistance to disinfectants, and it should be supported by different studies on biofilm elimination. In this study, the effectiveness of three commonly used disinfectants (chlorine tablet, peracetic acid-based disinfectant and lactic acid-based disinfectant) against L. monocytogenes biofilms on the main surfaces in contact with food, including stainless steel 316, epoxy and PVC, at the determined concentration and at different times were evaluated. In order to determine the antimicrobial activity of disinfectants, Listeria monocytogenes ATCC 7644 and Listeria monocytogenes (foodborne) strains were tested by using the liquid microdilution method. It was determined that the MIC and MBK values of the peracetic acid-based disinfectant and chlorine tablet used were lower than the lactic acid-based disinfectant. MIC and MBK values of all disinfectants were equal in both strains. By forming a biofilm with 2 strains of L. monocytogenes on stainless steel 316, epoxy and PVC surfaces, the effect of disinfectants was examined by trying different times on the MBK concentrations of the disinfectants. It was determined that the chlorine tablet applied for 30 seconds on stainless steel surfaces inhibited all microorganisms and was the most effective disinfectant for both strains on this surface. While peracetic acid-based disinfectant inhibited 100% of microorganisms in 30 seconds on epoxy surfaces with L. monocytogenes ATCC 7644 biofilm, it was found that all microorganisms were killed by peracetic acid-based disinfectant application for 1 minute on epoxy surfaces with L. monocytogenes (foodborne) strain. On PVC surfaces with L. monocytogenes ATCC 7644 biofilm, all microorganisms were inhibited in 15 minutes (4.75 log cfu/coupon reduction) of chlorine tablet and 60 minutes (4.91 log cfu/coupon reduction) of peracetic acid-based disinfectant. With the application of lactic acid-based disinfectant on the same strain and surface for 90 minutes, a reduction of 4.39 log cfu/coupon was achieved. It was determined that all microorganisms were inhibited by 30 minutes of chlorine tablet (4.92 log cfu/coupon reduction) applications on PVC surfaces with L. monocytogenes (foodborne) biofilm.